MSE HW 9

Which one of the following is yield strength? A. 300 MPa B. 350 MPa C. 200 MPa D. None of the above

A. 300 MPa

Which one of the following will not lead to plastic deformation? A. Bond stretching B. Dislocation movement C. Sliding of entangled long-chain molecules D. None of the above

A. Bond stretching

In the Maxwell model, which element dissipates energy? A. Dashpot. B. Spring. C. Both spring and dashpot can dissipate energy. D. None of above is correct.

A. Dashpot.

Modulus of a thermoplastic polymer _____ with increasing temperature. This behavior is particularly dominant above glass transition temperature. A. Decreases B. Increases C. Does not change

A. Decreases

Young's modulus is also known as ______? A. Elastic modulus B. Plastic modulus C. Loss modulus D. None of the above

A. Elastic modulus

A hypothetical material with a Poisson ratio of -0.1 will _____________ in lateral dimensions when under uniaxial tension. A. Expand B. Shrink

A. Expand

Aligned thermoplastic polymers exhibit _____ modulus in the direction of alignment than unoriented thermoplastic polymer. A. Higher B. Lower

A. Higher

Which material has the lowest ductility? A. Material I B. Material II C. Material III

A. Material I

Which strain represents the permanent plastic deformation? A. OC B. CD C. OD D. None of the above

A. OC

Which point represents the limit of linear elastic strain? A. Point A B. Point B C. Point C D. None of the above

A. Point A

In Maxwell model, elastic spring and viscous dashpot are connected in _______. A. Series B. Parallel C. Both series and parallel D. None of the above

A. Series

Definition of tensile modulus is __________. A. Stress/strain B. Stress x strain C. Strain/stress D. None of the above

A. Stress/strain

Toughness in tensile test is defined as _______________. A. The area underneath the stress-strain curve B. The highest stress C. The maximum elongational strain D. The fully recoverable strain

A. The area underneath the stress-strain curve

Diamond is an example of a very high modulus material. This statement is ______. A. True B. False

A. True

Elastic deformation is fully recoverable. This statement is ____? A. True B. False

A. True

For most materials, the true stress is higher than the engineering stress. This statement is _____. A. True B. False

A. True

Griffith equation is only applicable for brittle materials and not for ductile materials. This statement is _______. A. True B. False

A. True

Griffith theory predicts that theoretical strength of a material is about 10 % of its Young's modulus. This statement is ______. A. True B. False

A. True

Modulus of BCC iron along <111> is ~ 280 GPa, while along <100> is ~ 125 GPa. The modulus of polycrystalline iron is ~ 200 GPa. These statements are______? A. True B. False

A. True

For isotropic material, relationship between tensile modulus and shear modulus is given by which of the following equation? A. 𝐺=𝐸/3(1―2𝑣) B. 𝐺=𝐸/2(1+𝑣) C. 𝐺=2/𝐸(1+𝑣) D. None of the above

B. 𝐺=𝐸/2(1+𝑣)

In a stress relaxation test, stress as a function of time can be approximated by which one of the following equations? (Symbols have their usual meaning) A. 𝜎(𝑡)=𝜎0exp (𝑡/𝜏0 ) B. 𝜎(𝑡)=𝜎0exp (―𝑡/𝜏0 ) C. 𝜎(𝑡)=exp ( 𝑡/𝜏0 ) D. 𝜎0=𝜎(𝑡)exp (―𝑡/𝜏0 )

B. 𝜎(𝑡)=𝜎0exp (―𝑡/𝜏0 )

Rubber typically has a Poisson ratio close to____________? A. 0 B. 0.3 C. 0.5 D. 1

C. 0.5

Which one of the following is the strain to failure? A. 1% B. 2 % C. 6% D. None of the above

C. 6%

Definition of strain is ________? A. Original length/change in length B. Original length x change in length C. Change in length/ original length D. None of the above

C. Change in length/ original length

Which material has the lowest modulus? A. Material I B. Material II C. Material III

C. Material III

For an incompressible material, the Young's modulus (E) is ____________ times the elastic shear modulus (G). A. One B. Two C. Three D. Four E. None of the above

C. Three

For an incompressible material, the elastic bulk modulus is equal to ____________. A. 0 B. 1 C. infinity D. None of above

C. infinity

For a viscous material, which one the following equation is applicable? (Symbols have their usual meaning) A. 𝜎=𝐸𝜀 B. 𝜏=𝐺𝛾 C. σ=η(𝑑𝜖/𝑑𝑡) D. None of the above

C. σ=η(𝑑𝜖/𝑑𝑡)

According to Hooke's law, which of the following is correct? (Symbols have their usual meaning) A. 𝜎∝(1/𝜖) B. 𝜎∝(1/𝜖)^2 C. 𝜎∝𝜖 D. None of the above

C. 𝜎∝𝜖

Which one of the following is the initial modulus? A. 100 MPa B. 150 MPa C. 200 MPa D. 20 GPa E. None of the above

D. 20 GPa

Which material property has a unit different from the other three?A. Young's modulus B. Tensile strength C. Yield stress D. Poisson ratio

D. Poisson ratio

Which of the following is an example of high modulus material? A. Plexiglass (PMMA) B. Polypropylene C. Polystyrene D. Stainless steel.

D. Stainless steel.

On a tensile stress-strain curve, which value is the highest? A. Stress at the elastic limit B. Stress at the yield point C. Stress at fracture D. Tensile strength

D. Tensile strength

Which one of the following figures represents the stress-strain curve of a ceramic material? A. a B. b C. c D. d

D. d

Modulus can be measured in which of the following mode? A. Tension B. Compression C. Torsion D. Bending E. Shear F. All of the above

F. All of the above

Which one of the following is ultimate strength? A. 300 MPa B. 350 MPa C. 200 MPa D. None of the above

B. 350 MPa

Creep behavior is measured at _________. A. Constant strain B. Constant stress

B. Constant stress

In Griffith equation, 𝜎 = sqrt(2𝐸𝛾/𝜋𝑎), a is two times the crack length. This statement is ______. A. True B. False

B. False

Plastic deformation is fully recoverable. This statement is ____? A. True B. False

B. False

The elongation to break increases as the deformation rate increases in silly putty. This statement is ______. A. True B. False

B. False

Definition of stress is ________? A. Force x cross-sectional area B. Force/cross-sectional area C. Force/change in length D. Force x change in length

B. Force/cross-sectional area

Which material has the highest toughness? A. Material I B. Material II C. Material III

B. Material II

Which region represents the recoverable work? A. Region 1 B. Region 2 C. Region 1 + Region 2 D. None of the above

B. Region 2

In which test is the strain maintained constant? A. Creep test. B. Stress relaxation test.

B. Stress relaxation test.